Stebeofticon-slede



T. M. WATSON.

STEREOPTICON SLIDE.

APPLICATION FILED MAR. 24. 1919.

Patented Sept. 9, 1919.

INVENTOB .7/1 M44750 Law A woe/v5 rs UNITED STATES PATENT OFFICE.

TO'WLE M. WATSON, 0F BROOKLYN, NEW YORIL STEREOPTICON-SLIDE.

Specification of Letters Iatent.

Patented Sept. 9, 1919.

Application filed March 24, 1919. Serial No. 284,577.

lowing is a 'full, clear, and exact description.

The present invention relates to new and useful means in slides for stereopticon projectors, and has for its primary object to provide means for use in connection with glass plates to permit of their use with high power projectors.

It has been found that in projecting apparatus of the high-power type, the use of glass plates for carrying the matter projected has been prohibitive for the reason that said plates were too perishable to withstand the degree of heat to which they are subjected.

Referring to the drawings- Figure 1 is a front elevation of a stereopticon slide constructed in accordance with the present invention;

Fig. 2 is a rear elevation thereof' Fig. 3 is a sectional view on the line 3-3 of Fig. 1;

Fig. 4 is a view in elevation of the blank from which the holder is formed, and

Fig. 5 is an edge view of the device with the plates in place.

Referring more particularly to the drawings, the reference characters 10 and 11 designate two glass plates,one of these plates 10 being adapted to be provided in any suitable manner with the matter to be projected upon the screen, and the other plate 11 being plain on both its surfaces.

The reference character 12 designates a frame which is formed of relatively thin sheet metal, and said frame has its outer corners removed, as indicated by the reference character 13. The side and end edges of the frame are cut or severed, as at 14, at points intermediate of their ends, to rovide a plurality of wing sections 15, w ich are arranged around the marginal edge of the frame 12. a

After the side edges have been cut, as above described, the wing sections 15 are adapted 'to be folded in opposite directions upon the dotted lines 16, in which position they serve as retaining clips 17 for the glass plates 10 and 11.

In assembling a stereopticon slide constructed in accordance with the present invention, the glass plates 10 and 11 are positioned on opposite sides of the frame 12, and the wings 15 bent in alternate directions into engagement with said glass plates.

By this construction, it will be seen that the glass plates 10 and 11 are maintained in position with an intervening space 18, said space being equal to the thickness of the metallic frame 12. When the vplates are thus held in spaced relation, it W111 be seenthat a circulation of air between the plates 10 and 11 is permitted, which tends to cool the same to a degree preventing rapid expansion thereof under the influence of the heat from the light rays of the projector. Furthermore, by forming the frame 12 and the plate-retaining wings 15 of thin metal, any expansion of the plates 10 and 11 is readily taken care of through the flexibility of said metal.

From the foregoing description, it will be apparent that the present invention provides a holderfor stereopticon slides, the use of which permits of a free circulation of air between the plates of the slide, and, at the same time, provides for expansion of the glass when subjected to high degrees of temperature, thus permitting the use of glass for the purpose desired, which use has hereto'fore been prohibitive, as above stated.

It is to be understood that the frame 12 may be made in any desired size, this depending upon the size of the plates 10 and 11. In each case, however, the frame 12 Wlll be of a size slightly greater than that of the plates 10 and 11, as clearly shown in Fi 1 and 2.

aving thus described the invention, what is claimed is:

1. A device of the character described comprising a substantially rectangular frame provided at its corners with cutout portions, scoring lines connecting the inner corners of the cut-out ortions and defining projecting portions w ich are severed intermediate of their ends to permit of said projecting portions being bent in opposite directions to each other, and transparent plates secured upon opposite sides of said rectangular frame by the oppositely bent comprising a prisin a substantially rectangular frame provi ed at its corners'vyith cut-out portions, scoring lines connecting the inner corners of said cut-out portions and defining rectangular 7 frame provided at its cornerswith cut-out portions, scoring lines connectingthe inner corners of the cut-out portions and defini projecting portions on the sides of sai rame, and transparent plates secured upon opposite sides of said rectangular frame by bending the projecting portions into engagement with'said plates and within the confines of the scoring lines connectingthe corners of the cut-out portions of the frame.

TOWL E M. WATSON. 

